Safety mechanism for military fuzes

ABSTRACT

A safety mechanism for military fuzes. The mechansim includes a tab on the fuze rotating member adapted to extend over a portion of the rear fitting. A slider and an associated spring in the rear fitting normally prevents rotation of the arming shaft of the fuze. Movement of the slider to free the arming shaft is controlled by the tab. At conventional settings of the fuze, slider movement is not blocked by the tab and the slider is free to move into an annular groove in the fuze non-rotating member under the influence of the centrifugal force generated by projectile spin.

Elite States Pate abinowitz et a1.

11] 26,394 July 3.0, 1974 SAFETY MECHANHSM FOR MHLETARY FUZES [75] Inventors: Azriel J. Rabinowitz; John .1. (Jenna,

both of Rochester, NY.

[73] Assignee: The United States of America as represented by the Secretary of the Navy, Washington, DC.

8/1960 Hale 102/82 X 8/1960 Mantel 102/79 X Primary Examiner-Samuel W. Engle Attorney, Agent, or Firm-R. S. Sciascia; R. Schneider; W. A. Sivertson 5 7] ABSTRACT A safety mechanism for military fuzes. The mechansim includes a tab on the fuze rotating member adapted to extend over a portion of the rear fitting. A

slider and an associated spring in the rear fitting normally prevents rotation of the arming shaft of the fuze. Movement of the slider to free the arming shaft is controlled by the tab. At conventional settings of the fuze, slider movement is not blocked by the tab and the slider is free to move into an annular groove in the fuze nonrotating member under the influence of the centrifugal force generated by projectile spin.

3 Claims, 5 Drawing Figures AFENIEB JUL 3 0 I974 INVENTORS AZR/EL J. RAB/NOW/TZ JOHN J. CAMA ATTORNEY I I SAFETY MECHANISM FOR MILITARY FIJZES STATEMENT OF GOVERNMENT INTEREST The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

BACKGROUND OF THE INVENTION This invention relates generally to military fuzes and more specifically to a safety mechanism for such fuzes.

Controlled variable time (CVT) fuzes of conventional design contain a component identified as the rear fitting which is designed to prevent arming of the fuze during prelaunch storage and handling and for a suffrcient interval after launching to assure the safety of the firing crew. Arming is eventually accomplished by the effects of forces peculiar to the launch and post launch environments such as is generated by axial acceleration and spin rate.

In the case of rocket launched projectiles, the prelaunch safety provided by the rear fitting can be defeated. Accidental ignition of the rocket motor during storage or handling may prematurely launch the projectile in an uncontrolled fashion. In such a case, should the normal post-launch environment be achieved, the fuze will arm.

SUMMARY OF THE INVENTION The present invention provides a mechanism which permits CVT and other spin stabilized military fuzes to be set so that the fuze cannot arm. It provides an external means to manually set the fuze at the manufacturing source so that rear fitting arming is positively blocked. The block is automatically removed when the firing crew, as a part of their normal procedure, set the fuze, just prior to projectile launching, to select one of a number of alternative fuze operation sequences. Thus, accidental detonation of a projectile inadvertently launched is prevented even though the postlaunch environment approaches that encountered during a normal launching sequence.

OBJECTS OF THE INVENTION An object of the present invention is the provision of a afety mechanism to prevent accidental detonation of military fuzes.

Another object is to provide a mechanism that may be manually set so that the fuze cannot arm.

A further object is the provision of a mechanism that prevents accidental detonation of a projectile prior to normal launching when the prelaunch environment may otherwise cause the fuze to arm.

Other objects, advantages and novel features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a prior art controlled variable time fuze;

FIG. 2 is a partial cutaway showing the relationship of pertinent elements in the fuze of FIG. 1;

FIG. 3 shows a preferred embodiment of the present invention;

FIG. 4 is a partial cutaway showing the relationship of pertinent elements of the embodiment of FIG. 3; and

FIG. 5 is a section taken along line 5-5 in FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 1, there is shown a typical prior art CVT fuze. Rear fitting is prevented from rotating in fuze non-rotating member II by a key 12. To accomplish the fuze setting operation, just prior to projectile launching, a fuze rotating member 13 is turned with respect to the fuze non-rotating member 11. The final event required to arm the rear fitting 10 is rotation of an arming shaft 14 (see FIG. 2).

Referring now to FIGS. 3-5, there is shown a CVT fuze employing a preferred embodiment of the present invention. Rear fitting 20, fuze non-rotating member 21, key 22, fuze rotating member 23, and arming shaft 24 perform the same basic functions as the similarly designated elements of the conventional prior art CVT fuze of FIGS. 1 and 2.

A tab 26 extending over a portion of the rear fitting 20 has been added to the fuze rotating member 23. An annular groove 27 has been cut into fuze non-rotating member 21 (see FIG. 3) and a flat surface has been provided on arming shaft 24 (see FIG. 5). A slider 29 and an associated spring 30 are located within rear fitting 20.

With the slider 29 positioned as shown in FIG. 4 and- /or 5 arming shaft 24 is prevented from rotating by the action of slider 29 upon the flat surface of arming shaft 24. The spring 30 associated with the slider 29 serves to hold the slider 29 in this position. With the slider 29 abutting the flat surface of arming shaft 24 the fuze rotating member 23 can be oriented with respect to the fuze non-rotating member 21 such that the tab 26 prevents movement of the slider 29. With rotation of the arming shaft 24 thus prevented, the possibility of prematurely arming the rear fitting 20 is eliminated.

The fuze rotating member 23 can be indexed freely to any orientation required to select normal fuze operation sequences or to select the safe setting. The safe setting position is located so as not to interfere with other conventional fuze setting positions.

At the conventional setting positions, the tab 26 attached to the fuze rotating member 23 does not block movement of the slider 29. Such a setting is shown in dotted lines in FIG. 5. With the fuze rotating member 23 set at one of the normal fuze operation sequences, the slider 29 is free to move into the annular groove 27 under the influence of centrifugal force generated by projectile spin and the anning shaft is free to rotate in the normal manner. The orientation between the fuze elements at which the safe setting pertains is indicated by marking (not shown) on the external surfaces of the fuze members.

From the above it can be seen-that the application of the teachings of this disclosure to CVT fuzes provides external manual control over operation of the arming shaft in the rear fitting. The arming shaft in the rear fitting. The same basic approach can also be used to control movement of other types of arming triggers such as levers or sliders.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings.

What is claimed is: 1.1n combination with a military fuze of the type having a rear fitting, fuze rotating member, fuze nonrotating member and an arming shaft, the improvement which comprises:

a flat surface on said arming shaft; a slider within said rear fitting and movable between a first position in which the slider contacts the flat surface of the arming shaft and by such contact prevents rotation of the arming shaft, and a second position in which there is no slider-arming shaft contact; and a tab extending from said fuze rotating member and rotatable with the fuze rotating member into a plulaunch environment are achieved. 

1. In combination with a military fuze of the type having a rear fitting, fuze rotating member, fuze non-rotating member and an arming shaft, the improvement which comprises: a flat surface on said arming shaft; a slider within said rear fitting and movable between a first position in which the slider contacts the flat surface of the arming shaft and by such contact prevents rotation of the arming shaft, and a second position in which there is no slider-arming shaft contact; and a tab extending from said fuze rotating member and rotatable with the fuze rotating member into a plurality of settings, one of said settingS positioning said tab in a manner to positively block said slider in the first position.
 2. In the combination of claim 1 the further improvement comprising an annular groove within said fuze non-rotating member positioned to receive a portion of said slider when said slider is in the second of the two positions.
 3. In the combination of claim 1 the further improvement comprising a spring associated with said slider to maintain said slider in the first position during handling and until the centrifugal forces of the normal post-launch environment are achieved. 